A beam disposed along the width direction of a vehicle is provided at a lower position of a seat in the vehicle. The seat in the vehicle is connected to a vehicle body frame as the beam is coupled with an upper position of a vehicle attaching portion. As a vehicle having such a vehicle body structure, a seat for an automobile which transmits a collision load to be input to a vehicle door due to a side collision to a floor via an arm and a seat attaching portion which extend in a vehicle width direction below the seat is conventionally known (for example, Patent Citation 1). In this seat for an automobile, a plurality of seat-side reinforcing members that extend in the vehicle width direction is provided. An end of each seat-side reinforcing member is formed so as to protrude from a seat cushion, and the seat-side reinforcing member is connected to and supported by a strength member which extends between the ends of the plurality of seat-side reinforcing members in the front-back direction of the automobile.